Soil wetting pattern monitoring is a key factor in precision irrigation of grapevines

Abstract

Non-uniform Soil Wetting Patterns are commonly found in the field and numerical or empirical models developed to characterise them may or may not be accurate. Quantitative assessment of non-uniform wetted zones is essential for optimal irrigation management of crops under precision irrigation techniques such as Regulated Deficit Irrigation (RDI) or Partial Root-zone Drying (PRD). A field study was carried out to visualise the wetting pattern in situ on Grapevines (Vitis vinifera var. Cabernet Sauvignon) at Pencahue VII Region, Chile (University of Talca) and (Vitis vinifera var. Shiraz) at Richmond NSW, Australia (University of Western Sydney). In Chile, soil moisture and soil wetting pattern volumes were correlated with plant water status, measured as stem water potential (Ψstem) on RDI treatments. In Australia soil moisture data were collected using an array of capacitance probes (Sentek Pty. Ltd.) and used to generate 3D real time animations of soil wetting patterns at different irrigation systems (drip and sub-surface drip) using WPA© (Wetting Pattern Analyser), which is a novel software tool for visualisation and animation of field soil wetting patterns. Preliminary results have shown the critical importance of the location of soil moisture probes to schedule irrigation and a strong correlation of total available water in the wetted zone, (r2 = 0.77) and normalised soil moisture (r2 = 0.84) with Ψstem.